Recently, the quantity of antenna devices equipped in radio communication equipments such as mobile phones and PDAs (Personal Data Assistance) is growing with the increase of communication systems. Thus, such an antenna device should be improved so that a single antenna element is able to respond to multiple communication systems. Also, it is considered to be necessary to make recent radio devices respond to multiple communication systems such as GPS (Global Positioning System), Bluetooth (a registered trademark) or LTE (Long Term Evolution) at the same time. The antenna device disclosed in Patent document 1, for example, is an antenna device meeting such requirements.